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采用自溶-超声波耦合法提取啤酒废酵母中β-1,3-D-葡聚糖。首先以自溶率为考察指标,将单因素和正交实验相结合,结果显示,pH=5.0条件下,质量分数5%NaCl和体积分数1.5%乙酸乙酯混合添加可以最大限度地促进酵母细胞的自溶,从而促进酵母细胞质壁分离。进而,采用超声波法从自溶后收集的细胞壁沉淀中提取β-1,3-D-葡聚糖,以质量分数2%NaOH作超声溶剂,利用Box-Behnken设计考察了超声功率、超声时间和超声次数对葡聚糖提取率的影响,确定最佳提取条件为:超声功率550 W,超声时间33 min,超声次数2次,在该条件下葡聚糖提取率达到50.5%,与纯超声波提取葡聚糖法相比提取率提高了2倍。 相似文献
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采用自溶-超声波耦合法提取啤酒废酵母中β-(1,3)-D-葡聚糖。首先以自溶率为考察指标,将单因素和正交试验相结合,结果显示pH5.0条件下,5% NaCl和1.5 %乙酸乙酯混合添加可以最大程度的促进酵母细胞的自溶,从而促进酵母细胞质壁分离。进而采用超声波法从自溶后收集的细胞壁沉淀中提取β-(1,3)-D-葡聚糖,以2% NaOH作超声溶剂,利用Box-Behnken设计考察了超声功率,超声时间和超声次数对葡聚糖提取率的影响,确定最佳提取条件为:超声功率550W,超声时间33min,超声次数2次,在此条件下葡聚糖提取率达到50.5%,与纯超声波提取葡聚糖法相比提取率提高了2倍。 相似文献
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番茄红素提取方法的研究 总被引:35,自引:0,他引:35
研究了从番茄中提取番茄红素的方法 ,考察了提取温度、时间、料液比、浸取液等影响因素 ,确定了最佳的浸取工艺条件。使用 6# 溶剂油二级浸提番茄糊 ,在番茄糊质量与溶剂体积比为 0 33g/ml、浸提时间 2~ 3h、pH值 6、浸提温度 35℃及加入助剂条件下 ,能充分提取色素 ;若使用微波辐射法 ,在微波功率 2 0 0W、萃取时间 80s,番茄糊质量与溶剂体积比为 0 5g/ml条件下 ,能得到最好效果 相似文献
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溶胶凝胶法氧化铝分离膜制备工艺探讨 总被引:1,自引:0,他引:1
以异丙醇铝为主要原料,将原料子处理后,用溶胶-凝胶法制备Al2O3,膜,考察胶溶剂的种类和用量、水解温度、回流时间等制备条件对Al2O3,膜微观结构的影响。研究结果表明,选择用HCl作为胶溶剂,调节溶液pH值为2.O-3.5、水与乙醇体积量比为1:1、水解温度为80~85℃左右。通过预处理,合成时间缩短,为6~8h左右,可以制得微观结构性能比较好的Al2O3膜。 相似文献
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目的优化毕赤酵母工程菌GS115/xyn11A产重组木聚糖酶的发酵条件,并检测其酶学性质。方法采用单因素试验和L(934)正交试验考察摇瓶发酵条件下培养基起始pH值、诱导剂甲醇添加量、诱导温度及诱导时间对产酶活性的影响;并分析重组木聚糖酶的酶学性质。结果影响重组毕赤酵母产酶的因素重要性依次为:培养基起始pH值>诱导时间>诱导温度>甲醇添加量,重组酵母产酶最佳条件为:起始pH值7.5,甲醇添加量1.5%,32℃诱导96 h,在此条件下进行诱导表达重组木聚糖酶的酶活性可达228.35 IU/ml;酶的最适反应温度为50℃,最适反应pH值为5.5,在低于40℃和pH 4.5~7.5的范围内较稳定。结论优化了毕赤酵母产重组木聚糖酶的发酵条件,为木聚糖酶的工业化生产及应用提供了依据。 相似文献
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红霉素衍生物中间体红霉素A肟的合成新工艺 总被引:1,自引:0,他引:1
以硫氰酸红霉素为原料、盐酸羟胺为肟化剂、三乙胺为碱、甲醇为溶剂“一锅法”合成了新型红霉素衍生物通用中间体红霉素A肟,考察了各条件对反应收率的影响。结果表明,反应最佳条件为:原料配比n(硫氰酸红霉素):n(盐酸羟胺)=1:8.5,pH=6.5~6.9,温度50~55℃,时间24h,此时收率85.2%;重结晶时,滴水温度40~50℃。产品HPLC分析的质量分数97.8%,并经熔点测定、元素分析、IR和^1H NMR进行确认。与其他肟化工艺相比,产品的生产成本可明显降低。 相似文献
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Julie Barrette Claude P Champagne Jacques Goulet 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2001,76(2):203-209
The effect of the autolysis conditions of bakers' yeast on the growth‐promoting properties of the resulting yeast extracts (YE) were examined on cultures of Lactococcus lactis ssp lactis D25 and of Lactococcus lactis ssp cremoris R2. The various YE were produced by conducting autolysis at four pH levels (pH 4.0, 5.5, 7.0 or 8.5) and with or without the autolysis promoters (AP) ethyl acetate or chitosan. To determine if the presence of contaminating bacteria during autolysis affected the YE characteristics, one series of YE was also prepared with the bakers' yeast cell suspension contaminated with 108 CFU/cm?3 of typical yeast plant bacteria (mostly of the Bacillus genus) at the beginning of autolysis. The growth curves of the lactococci in media supplemented with the various YE were analyzed to determine the maximum optical density (ODmax), the maximum growth rate (µmax) and the fermentation time (F‐time) at which ODmax was reached. The addition of bacterial contaminants (at 108 CFUcm?3) did not significantly influence the growth‐promoting properties of YE. The lactococci had higher ODmax and µmax values when the media contained YE produced at pH 4.0 or 5.5, and these YE contained 40% more total nitrogen than those obtained at pH 7.0 or 8.5. There was no major effect of AP on the biological value of the resulting YE, but a significant interaction between pH and AP was found for L lactis D25. Thus the ODmax of YE produced at pH 7.0 and 8.5 were highest when ethyl acetate was used as autolysis promoter, as compared with control and chitosan at pH 7.0–8.5, while the opposite was obtained with products produced at pH 4.0 and 5.5. This study shows that parameters used to produce YE influence their biological value with respect to the growth‐promoting properties of lactococci. © 2001 Society of Chemical Industry 相似文献
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2-羟丙基三甲基氯化铵壳聚糖的制备及其表征 总被引:18,自引:0,他引:18
以脱乙酰度为90%的壳聚糖(CTS)为原料,异丙醇为溶剂,w(NaOH)=40 0%的水溶液为催化剂,3 氯 2 羟丙基三甲基氯化铵(CTA)为改性剂,在m(NaOH)∶m(CTS)=1 0∶1 0,m(CTA)∶m(CTS)=4 0∶1 0,反应温度65 0℃下制备了2 羟丙基三甲基氯化铵壳聚糖(HTCC)。实验结果表明,在反应时间达到或超过9 0h时,得到的HTCC产品的接枝度超过90 0%,在pH=6 7~7 0的水中可完全溶解形成w(HTCC)=3 0%的溶液。IR和1HNMR的结果表明,接枝反应主要发生在CTS的氨基上。 相似文献
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制备了具有洁牙、护牙、抗菌消炎作用的高粘度、多功能过氧化脲洁牙凝胶。该凝胶无毒、无副作用 ,在口腔应用中粘度稳定 ,避免唾液溶解 ,使洁牙成分持久释放 ,提高洁牙效率。研究了过氧化脲的制备方法 ,所制备的过氧化脲质量分数大于 98%。所制备的齿科材料为粘度 30 0~ 4 5 0Pa .s,pH值 5~ 7的无色透明凝胶 ,含过氧化脲质量分数 6 %~ 2 0 % ,稀释剂 4 0 %~ 80 % ,增稠剂 4 %~ 10 % ,pH调节剂 2 %~10 %及稳定剂、抗过敏剂、护牙剂、调味剂等成分。 相似文献
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硅烷偶联剂对龙岩高岭土表面改性的研究 总被引:1,自引:0,他引:1
采用硅烷偶联剂KH-540对龙岩高岭土进行表面改性处理,研究了偶联剂的用量、表面改性处理的pH值、改性温度、反应时间等因素对高岭土活化指数的影响。以高岭土在液体石蜡中的沉降体积和红外光谱(FT-IR)等手段研究了改性效果以及改性剂与高岭土之间的相互作用。结果表明,改性的最佳实验条件为:偶联剂用量为2%左右,改性pH在8~10,改性温度为60℃,反应时间40 min。高岭土经过活化处理后,在液体石蜡中的分散性和稳定性均得到明显提高;偶联剂与高岭土之间以化学键合作用为主。 相似文献
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硫氢化钠法常压合成巯基乙酸 总被引:2,自引:0,他引:2
研究了以硫氢化钠和氯乙酸钠为原料常压合成巯基乙酸。适宜工艺条件为 :硫氢化钠溶液 pH值在 9左右 ,浓度为 0 65~ 0 70mol·L- 1,相应的氯乙酸钠溶液浓度为 2 0~ 1 5mol·L- 1,氯乙酸钠和硫氢化钠配比为 1∶1 3(mol) ,反应温度为 5 5± 1℃ ,反应时间为 12min ,巯基乙酸的收率为 82 %~ 87%。 相似文献
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高稳定性多羟甲基三聚氰胺初缩体的合成 总被引:3,自引:0,他引:3
采用甲醚化使多羟甲基三聚氰胺初缩体溶液的稳定性达到满意效果。研究了反应物的浓度、介质pH、温度及反应时间对合成的影响,测定了初缩体的红外光谱。最佳合成条件为:三聚氰胺(mol)∶甲醛(mol)∶甲醇(mol)=1∶(3.5~6)∶(4~7);羟甲基化pH=75~9,温度70~90℃,时间05~15h;醚化缩合反应pH=4~7,温度50~70℃,时间05~2h。 相似文献
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A. Wiseman P. R. Jones 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1971,21(1):26-28
A variety of disruption techniques were used on brewers' yeast with subsequent estimation of the additional (assay-increment) α-glucosidase and invertase made accessible to p-nitrophenylglucoside (PNPG) and sucrose, respectively, in the total disruptate. The extent of actual solubilisation of these two enzymes in the 0.75 M potassium phosphate buffer (pH 6.5) present, was also measured. Extensive release (i.e. solubilisation) of α-glucosidase was achieved using ultrasonication or ethyl acetate autolysis, and here differential release of α-glucosidase over invertase was large. Extensive release of both α-glucosidase and invertase was obtained with snail gut enzyme and toluene (papain) autolysis, while air drying released some invertase but destroyed 80% of the α-glucosidase. The assay-increment, over intact yeast values, for α-glucosidase in total disruptate, which is due to increased accessibility of PNPG to this enzyme, was high for salt autolysis and toluene (papain) autolysis but was low for the Mickle shaker and the Potter-Elvehjem homogeniser. No increment was observed using the X-press, although solubilisation of α-glucosidase was moderately good. Increment, over intact yeast values, for invertase assay in total disruptate was highest with ultra-sonication and air drying, but was nevertheless generally low owing to almost complete availability of this cell wall enzyme for assay—but not for isolation—in intact yeast. 相似文献